1. Field of the Invention
The present invention relates to antenna devices and radio-wave receivers with such antenna devices.
2. Description of the Related Art
In the past, radio-wave receivers such as radio-wave controlled wristwatches are known which include an antenna device which receives standard radio waves including time information to set a current time automatically. Many radio-wave controlled timepieces include an antenna structure which comprises a core of a magnetic material such as amorphous metal or ferrite of high reception sensitivity around which core a coil is wound to receive standard radio waves.
As the core of the antenna structure is longer and its radio wave reception area is larger, the reception sensitivity of the antenna structure improves. If the antenna structure is provided within a small radio-wave receiver such as a wristwatch type radio-wave controlled timepiece, it must be small because a space within the timepiece.
Radio-wave receivers are known which use a small antenna structure which includes a core of layered strip-like amorphous layers, as disclosed in Japanese patent application KOKAI publications No. 2008-141387 and No. 2008-141389.
In these radio-wave receivers, the strip-like layers of the core are layered in the thickness direction of a circuit board or a module member of the radio-wave receiver layered on the circuit board within the receiver. Thus, when the antenna structure is disposed at a straight edge of the circuit board, extra space is needed, which corresponds to the width of the core. Thus, the antenna structure cannot be disposed efficiently within a limited inner space of the receiver. In order to ensure a space for accommodating the antenna structure, the case must be enlarged.